Production of flavor-changing gauge bosons fromE6ate+e−and hadron colliders

1988 ◽  
Vol 38 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Thomas G. Rizzo
2004 ◽  
Vol 19 (06) ◽  
pp. 405-419 ◽  
Author(s):  
NIKOLAOS KIDONAKIS

We review recent advances in the calculation of higher-order soft-gluon corrections for a variety of QCD, Higgs, and SUSY processes in hadron colliders. A unified approach and master formulas for next-to-next-to-leading order soft and virtual corrections are discussed. We present some applications of the formalism to top quark pair production at the Tevatron and the LHC, top production via anomalous couplings in flavor-changing neutral-current processes, W boson hadroproduction at large transverse momentum, and charged Higgs production at the LHC.


Author(s):  
J. I. Aranda ◽  
E. Cruz-Albaro ◽  
D. Espinosa-Gómez ◽  
J. Montaño ◽  
F. Ramírez-Zavaleta ◽  
...  

We calculate bounds for the branching ratio of the [Formula: see text] decay, for the first time, in the context of flavor changing neutral currents mediated by a [Formula: see text] gauge boson, which can arise from five extended models. In this sense, by using experimental measurements on the [Formula: see text] decay and the [Formula: see text] process, we look for constraints of the [Formula: see text] coupling, where the more restrictive bound is offered by the last one. On the other hand, by employing the experimental restriction on the [Formula: see text] decay, the strength of the [Formula: see text] coupling is estimated. Our analysis is based on the more recent experimental results on searches for the [Formula: see text] gauge boson in ATLAS and CMS detectors. In addition, we revisited the [Formula: see text] meson decays by using different approaches not previously reported. The strengths of the [Formula: see text] and [Formula: see text] couplings were estimated by employing experimental restrictions on the [Formula: see text] decay and the [Formula: see text] conversion rate, respectively. Thus, we predict the following upper bounds: [Formula: see text], [Formula: see text] and [Formula: see text].


2006 ◽  
Vol 21 (37) ◽  
pp. 2833-2843 ◽  
Author(s):  
XUELEI WANG ◽  
LILI YU ◽  
NAHONG SONG ◽  
WENNA XU

We study the associated production of the neutral top-pion [Formula: see text] with the third family quarks within the context of the topcolor-assisted technicolor model at the hadron colliders. The studies show that, at the Tevatron, the cross-sections of all these processes are too small to produce enough identified signals. But the cross-sections can be largely enhanced at the LHC. Specially for the processes [Formula: see text] and [Formula: see text], the cross-sections can reach the level of a few hundred fb even a few pb for the light neutral top-pion. With the high yearly luminosity 100 fb-1 at the LHC, over 104 signals can be produced via the above two processes. There exists an ideal flavor-changing mode to detect neutral top-pion, i.e. [Formula: see text], because the SM background of such production mode are very clean. Therefore, we can conclude that neutral top-pion should be observable at the LHC via the processes [Formula: see text] and [Formula: see text]. On the other hand, the statistics available at the LHC via these two processes might be enough to measure the Yukawa couplings [Formula: see text] and [Formula: see text]. Finally, it must be noted that the study of the process [Formula: see text] can give us a good chance to distinguish the TC2 model from the SM and MSSM because there does not exist such similar tree-level favor-changing process in these models.


1987 ◽  
Vol 02 (03) ◽  
pp. 831-890 ◽  
Author(s):  
B. A. CAMPBELL ◽  
J. ELLIS ◽  
K. ENQVIST ◽  
M. K. GAILLARD ◽  
D. V. NANOPOULOS

Superstring models compactified on Calabi–Yau manifolds contain additional matter fields and gauge bosons beyond those in the Standard Model. The new matter and gauge couplings would make additional contributions to conventional electroweak processes, generate extra flavor-changing neutral interactions, and mediate new interactions leading to proton decay and neutrino masses. We use the phenomenological constraints on such effects to derive upper bounds on Yukawa couplings in low-energy dynamical models inspired by the superstring. We draw attention to the processes which give the best bounds on new Yukawa couplings, and which are those where novel superstring effects might first appear as experimental sensitivity is improved. Our bounds are not sufficient to exclude most superstring models with additional light particles, but do suggest that some couplings are too small to realize certain scenarios for symmetry breaking by radiative corrections.


2019 ◽  
Vol 795 ◽  
pp. 371-378 ◽  
Author(s):  
Wei-Shu Hou ◽  
Rishabh Jain ◽  
Chung Kao ◽  
Masaya Kohda ◽  
Brent McCoy ◽  
...  

2015 ◽  
Vol 30 (32) ◽  
pp. 1550187 ◽  
Author(s):  
D. Cogollo

In light of the ongoing effort on reducing the theoretical uncertainties and an upcoming experiment concerning muon magnetic moment, we perform a detailed study of an 3-4-1 electroweak gauge extension of the standard model that contains exotic charged leptons in its spectrum. We discuss flavor changing neutral current, collider and electroweak bounds on the model and derive [Formula: see text] limits using current and projected limits on the muon magnetic moment. In summary, we exclude the masses of new gauge bosons that couple to muons and heavy charged leptons up to 700 GeV. Moreover, we find a projected lower bound on the scale of symmetry breaking to be 2 TeV.


2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
M.A. Arroyo-Ureña ◽  
T.A. Valencia-Pérez ◽  
R. Gaitán ◽  
J.H. Montes de Oca Y ◽  
A. Fernández-Téllez

Abstract We study the flavor-changing decay h → τ μ with τ = τ− +τ+ and μ = μ− +μ+ of a Higgs boson at future hadron colliders, namely: a) High Luminosity Large Hadron Collider, b) High Energy Large Hadron Collider and c) Future hadron-hadron Circular Collider. The theoretical framework adopted is the Two-Higgs-Doublet Model type III. The free model parameters involved in the calculation are constrained through Higgs boson data, Lepton Flavor Violating processes and the muon anomalous magnetic dipole moment; later they are used to analyze the branching ratio of the decay h → τ μ and to evaluate the gg → h production cross section. We find that at the Large Hadron Collider is not possible to claim for evidence of the decay h → τ μ achieving a signal significance about of 1.46σ by considering its final integrated luminosity, 300 fb−1. More promising results arise at the High Luminosity Large Hadron Collider in which a prediction of 4.6σ when an integrated luminosity of 3 ab−1 and tan β = 8 are achieved. Meanwhile, at the High Energy Large Hadron Collider (Future hadron-hadron Circular Collider) a potential discovery could be claimed with a signal significance around 5.04σ (5.43σ) for an integrated luminosity of 3 ab−1 and tan β = 8 (5 ab−1 and tan β = 4).


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